Duplex-pressure straight-air brake.



c. P. CASS. DUPLEXPRESSURE STRAIGHT AIR BRAKE.

APPLICATION PILBD MAYA, 1907.

977,164. Patented No.29,1910.

WITNESSES INVENTOR fill mama FSTEII 1:0 IISIIIHMBN, b. c.

UNl'lE STATES PAJENT @Tt FlCE.

CHRISTOPHER P. CASS, OF ST. LOUIS, MISSOURI, ASSIGNOB. TO THEW'ESTINGHOUSE AIR BRAKE COMPANY, OF PITTSBURG, PENNSYLVANI A VANIA.

COEKPOBATION OF PENNSYL- Application filed May 4, 1907.

To all whom it may concern:

Be it known that I, CrimsiorrrnR P. Cass, a citizen of the UnitedStates, residing at St. Louis, State of Missouri, have invented new anduseful Improvements in Duplex-Pressure Straight-Air Brakes, of which thefollowing is a specification.

My invention relates to fluid pressure brakes, and particularly to whatis known as straight air brakes.

The principal object of my invention is to provide improved means forlimiting the maximum degree of brake cylinder pressure in serviceapplications of the brakes, while in emergency applications a greatermaximum pressure may be obtained. F or this purpose my improvementscomprise means, such as a safety or blow down valve, which may be set tothe desired maximum degree of pressure, and means, preferably themotormans brake valve, adapted to establish communication between thesafety valve and the brake cylinder in service applications of thebrakes.

In the accompanying drawings, Figure 1 is a diagrammatic elevation of amotor car straight air brake equipment embodying one form of myinvention; Fig. 2 a central sectional view of the motormans brake valve,showing the position of ports when in lap position, with the brakecylinder open to the safety valve; Fig. 3 a plan view of the rotaryvalve seat of the brake valve, and Fig. 4 a face view of the rotaryvalve, showing the arrangement of cavities.

According to the construction shown, the car air brake equipmentcomprises a reservoir 1, which may be charged with air in any desiredmanner, such as by a motor driven pump 2, a reservoir pipe 3 extendingfrom said reservoir to a motormans brake valve 41, preferably one ateach end of the car, a straight air pipe 5 extending through the car andconnected to the brake valves and to the brake cylinder 6, and a safetyor blow down valve 7 connected by a pipe 8 to said brake valves.

The valve seat of the brake valve is provided with the usual ports 9, 10and 11 com municating respectively with the straight air pipe 5, theexhaust, and reservoir pipe 3, and in addition, has a port 12communicating with the safety valve pipe 8. The rotary valve 13 isprovided with cavity 14 having Specification of Letters Patent.

Patented Nov. .29, 1910.

Serial No. 371,888.

openings 15 and 16 on the valve face, adapted to register with the ports9, 10 and 11, and a radially arranged groove or cavity 17 adapted toconnect the straight air pipe port 9 with safety valve port 12 in lapposition.

Service applications of the brakes may be made in the usual way, bymoving the brake valve handle to service position, in which thereservoir pipe 3 is connected to the brake cylinder pipe 5 by the cavity1 1 in the ro tary valve 13. On returning the brake valve handle to lapposition, communication is established between the safety valve pipe 8and the brake cylinder pipe 5, and consequently, when the brake cylinderpressure rises above the desired degree for which the safety valve isset, the excess pressure is re lieved through the valve.

So long as the brake valve handle remains in service position, the brakecylinder pressure may be increased up to the limit of the pressure ofair in the reservoir, and the pressure may then be reduced to thepredetermined limit, by moving the brake valve handle to service lapposition. If desired, the safety valve may be open to the brake cylinderin the movement of the brake valve handle between service position andlap, and in this case the port 12 is provided with an eX- tension 19which registers with the cavity 17 when the valve is in serviceposition, so that the brake cylinder pressure will not rise above thelimit, for which the safety valve is set, when the valve is in serviceposition. In the emergency position, the safety valve is cut off fromthe brake cylinder, and full reservoir pressure may be obtained in thebrake cylinder.

It is preferable to provide cut out cook's 18 in the safety valve pipe 8near the brake valves 4, for the purpose of closing communication fromthe safety valve to a brake valve not in use, so that any possibility ofcommunication being open through the dead brake valve to the safetyvalve will be obviated, in case of an emergency application of thebrakes.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is 1. In a fluid pressure brake, thecombination with a reservoir, brake cylinder, straight air pipe and abrake valve for controlling the supply of air from the reservoir to thebrake cylinder, of means opening to the brake cylinder in serviceapplications for limiting the brake cylinder pressure.

2. In a straight air brake system, the combination with a reservoir,brake cylinder, straight air pipe and a brake valve for controlling thesupply-of air from the reservoir to the brake cylinder, of a safetyvalve adapted to be connected to the brake cylinder in serviceapplications for limiting the brake cylinder pressure to a predetermineddegree.

3. In a straight air brake system, the combination with a reservoir,brake cylinder, straight air pipe and a brake valve for controlling thesupply of air from the reservoir to the brake cylinder, of a safetyvalve for limiting the brake cylinder pressure and means in said brakevalve for opening communication between said safety valve and the brakecylinder in service applications of the brakes.

t. In a straight air brake system, the combination with a reservoir,brake cylinder, straight air pipe and a brake valve for controlling thesupply of air from the reservoir to the brake cvlinder, of a safetyvalve for limiting the brake cylinder pressure and means in said brakevalve for opening com munication between said safety valve and the brakecylinder in service applications of the brakes and for closing saidcommunication in emergency applications.

5. In a straight air brake system, the combination with a reservoir,brake cylinder, straight air pipe and a brake valve for controlling thesupply of air from the reservoir to the brake cylinder, of a safetyvalve for limiting the brake cylinder pressure, and means in said brakevalve for establishing communication between the safety valve and brakecylinder in the lap position of the brake valve.

6. In a fluid pressure brake, the combination with a brake cylinder anda safety valve for limiting the brake cylinder pressure, of a brakevalve for controlling communication from the brake cylinder to saidsafety valve.

In testimony whereof I have hereunto set my hand.

CHRISTOPHER P. CASS. Vitnesses C. H. BECK, 0. WV. TOWNSEND.

